Cooling of quantum systems through optimal control and dissipation

Coherent control of quantum dynamics is a powerful tool to drive a system towards desired states and to optimize properties of the dynamics. Mature numerical methods exist for the control of non-dissipative dynamics [1– 5]. Similar approaches to open quantum systems are urgently needed and evolving rapidly [6–8]. However, particular care is needed in this case, for which commonly used equations of motion are approximate. Strong driving does not only have an impact on the system, but the interaction between the control-modified system and the reservoir differs substantially from the case of autonomous dynamics. This basically calls Markovian and perturbative approaches into question. Instead of relying on these approaches, we propagate the quantum system using a fully non-Markovian, exact stochastic Liouvillevon Neumann equation [9]. Uniting this approach with optimal control theory allows the consideration of control signals of arbitrary strength and complexity [10].